So, if you run into any problems, you just should make sure that certain things are prepared and you can revert to Exchange Server 2003. This article will discuss the various preparations you should make during the various stages of the process and how to fix any problems that might occur.
General Preparation Tasks before the Transition
Before we start the Transition, you should review the event logs on all your Domain Controllers to make sure that no errors or warnings are in there. If you find any, you should correct them first before you go on. Additionally, you should make sure all Windows Updates are installed. DCDIAG.EXE from Windows Support Tools may help you during this task.
Afterwards you should back up the system state of all your Domain Controllers to make sure you are able to restore Active Directory in the event of a failure during the setup process.
Domain and Forest Preparation for Exchange Server 2007
In order to prepare the Active Directory Environment you will have to import some new schema entries. This means you will have to log on locally to your Domain Controller on which the schema role resides. Since this means a re-indexing of your Active Directory Database, I recommend doing this during non-work hours and if possible when running Active Directory Native Server 2003 forest mode. This would mean that we only have delta replications and no full replications like running on Windows Server 2000 mode. So you will have less replication traffic on your WAN links.
If you have trouble during the schema enhancement for Exchange Server 2007, your only chance to go back to Exchange Server 2003 is to completely restore System State on your Schema Master Domain Controller and hopefully it would not have replicated some entries during this phase, because this would mean restoring System State on all your Domain Controllers in your network environment. But don’t be angry, a restore of Active Directory is quite easy if you follow the following procedures:
- Start your Domain Controller in Active Directory Restore Mode.
- Log on with your Active Directory Restore Mode Logon Credentials.
- Restore System State from backup.
- Configure Authoritative Restore using NTDSUTIL.EXE.
- Restart your Domain Controller.
- Follow the steps above for all your Domain Controllers.
Troubleshooting the Implementation of Hub Transport Servers
The first Exchange Server 2007 box you might implement is the one on which the Hub Transport Role will reside. This box is quite easy to implement, you should move forward after having a good system state backup ready in the event of a failure. If something unplanned happens during the move of the general configuration settings to Exchange Server 2007, your disaster recovery plan is to restore Active Directory from backup.
Troubleshooting the Implementation of Mailbox Servers
After having set up the mailbox or database role servers, which could be a single or multiple server deployment, perhaps in addition with one of the high availability features of Exchange Server 2007 (Local Continuous Replication, Standby Continuous Replication, Cluster Continuous Replication, or Single Copy Cluster), we have to move the mailboxes from the old environment to the new one. This mailbox move is quite easy, too.
In general there should be no problems unless the user whose mailbox is currently being migrated is logged off. In general no problems should occur on the client systems, too: they should discover that their mailbox has moved to another server while they were offline. To insure this Exchange Server 2007 has a new functionality for automatic creation of MAPI profiles, if you have Outlook 2007 deployed. So make sure to have Outlook 2007 deployed before starting with the deployment of Exchange Server 2007 mailbox servers.
Troubleshooting the Implementation of Client Access Servers
The Client Access Server role provides functionalities like Outlook Web Access, Outlook Mobile Access (Exchange Push), etc. When migrating from other Exchange Server releases this is the first box you should implement (in general this will be your front end server machine), since this will allow Outlook Web Access to work on mailboxes that reside on older versions of Exchange and on Exchange Server 2007.
If anything failed during the implementation of this server, you just have to reinstall this machine and try again.
Troubleshooting the Implementation of Unified Messaging Servers
When implementing the Unified Messaging role, your disaster recovery plan during your deployment of Exchange Server 2007 is quite easy, because this is a new feature set that was not part of earlier releases of the product. In the event of an unexpected error, you just have to take a second chance and reinstall the server again.
Troubleshooting the Implementation of Edge Servers
The Exchange Server 2007 Edge Server Role is a solution that is placed in your DMZ to relay your emails into your Exchange Organization or outside it, so it is responsible for incoming and outgoing emails and is completely independent from your Active Directory, because it works with ADAM (Active Directory in Application Mode). If you run into problems during its implementation, you will have to start over again. If it is already running, you can run the ExportEdgeConfig.ps1 Powershell script to save the configuration in a XML file and use this for import purposes on the new server.
As you have seen in the sections above the transition from Exchange Server 2003 to Exchange Server 2007 is not a big risk if you plan the project and each project phase should include a plan to revert if something unplanned happens and there is no way to go on. These risk management procedures will insure that you minimize unavailability times in case of an error and that your email environment will work properly and be available most of the time.
Exchange Server 2007 with Service Pack 1 is a very stable and reliable solution. In my opinion, it is the best release Microsoft has come out with yet. So I think there is no reason for you to wait to migrate. Just create a project plan and your email server environment will survive the transition to Exchange Server 2007.
If you still have any questions, please do not hesitate to contact me.